Recently, the energy issue has become a serious problem not only domestically but also internationally. Especially fossil energy that is used most widely for power generation has a problem of energy depletion along with environmental pollution.
Thus, alternative energy is being developed all over the world, and nuclear energy can be mentioned as an example of alternative energy. But nuclear energy, which is currently a major alternative energy to fossil fuel, is controversial because of harmful effects due to nuclear waste disposal and radioactive effluents. Although there are power generation facilities using sunlight or wind power, they have a problem that it is difficult to get enough electric power depend upon circumstances. In addition, hydroelectric power generation requires high construction costs and a large area must be submerged to construct a dam, so it causes environmental destruction.
Taking these problems into account, tidal current power generators using kinetic energy of seawater are recently attracting attention. In general, tidal current power generation produces electricity by installing a generator in a place where the flow velocity of seawater is fast. It has advantages in that the movement of ships is unhindered depending on the installation method, and that it is an environmentally friendly alternative energy system which does not obstruct the movement of fish and does not affect the ecosystem around it, and that the amount of power generation can be estimated because the movement of seawater is regular.
Such tidal current power generators are installed mainly in an area where the seawater flow of flood tide or ebb tide is accelerated by topographical conditions because it should have a seawater flow of more than a certain speed in order to produce electricity by rotating turbines.
However, places where such a general tidal current power generator can be installed are limited and there is a limit to increasing the output by the flow velocity of given seawater, and there is a difficulty in securing economic viability by generation quantity, so its propagation has not yet widely expanded.